Abstract P15: Periodic Acceleration (pGz) Preconditioning in Swine Increases Endothelial Derived NO and Phosphorylated eNOS via Akt Pathway
Periodic acceleration (pGz) is the motion of the supine body using a motorized platform (3Hz & ±0.4G). pGz produces pulsatile shear stress increasing release of endothelial derived NO (eNO) which, also decreases myocardial stunning and improves outcomes from ventricular fibrillation (VF) cardiac arrest. Preconditioning with pGz (PRE-pGz) prior to VF cardiac arrest ameliorates global post resuscitation cardiac dysfunction and reduces arrhythmias. To test whether pGz and PRE-pGz increase eNOS and phosphorylated eNOS (p-eNOS) via the PI3-kinase-Akt pathway, anesthetized, intubated male swine (40 –50lbs) were studied. Five animals had no intervention (BL) and 5 received 1 hr pGz preconditioning (pGz) followed by Western Blot of myocardial tissue. Additional animals (10 per group) received 1 hr pGz (PRE-pGz) or no treatment (CPR-CONT). In the latter groups VF was electrically induced and unsupported for 8 min followed by continuous manual chest compression and defibrillation for 10 min or until return of spontaneous circulation (ROSC). PRE-pGz animals showed less hemodynamically significant arrhythmias after ROSC than CPR-CONT (35 vs 7; p<0.05) and less myocardial stunning. eNOS and phosphorylated-eNOS (p-eNOS) significantly increased after pGz and after CPR but were significantly higher in pGz preconditioned animals along with increased phosphorylated Akt (p-Akt). The graph below shows % changes relative to BL (M±SD). *p < 0.01 PRE-pGz vs CPR-CONT.
Conclusion: pGz applied prior to ischemia reperfusion injury increases eNOS and p-eNOS expression and increased p-Akt. Thus, pGz preconditioning protects myocardium during I-R in part by activating eNOS through p-Akt